Lock bolt for motor-vehicle door latch

ABSTRACT

A motor-vehicle door lock has a lock bolt defining an axis and normally secured to the doorpost. A locking fork normally secured to the door edge can engage this lock bolt to retain the door against the doorpost. The bolt is formed of a rigid axially extending metal core and at least one axially deformable synthetic-resin body on the core. The core has a plurality of annular ridges having outer surfaces and defining a plurality of outwardly open annular grooves and the body fills these grooves and projects radially therefrom beyond the outer surface of the ridges. The ridges and grooves may be separate and annular, or may be the turns of a helical screwthread formation.

FIELD OF THE INVENTION

The present invention relates to a motor-vehicle door latch. Moreparticularly this invention concerns a lock bolt for such a latch.

BACKGROUND OF THE INVENTION

A motor-vehicle door latch of the type described in commonly owned U.S.Pat. Nos. 3,997,202 and 4,097,078 has a lock bolt defining an axis andnormally secured to a doorpost. A locking element normally secured tothe door edge is engageable with this lock bolt to retain the dooragainst the doorpost. The locking element is normally formed as apivotal fork that can be retained in place around the lock bolt by apivotal lock pawl.

In order to minimize the noise generated by such a latch mechanism it isknown from German utility model 7,247,283 to provide an elastic coveringfor the region of the lock bolt engaged by the locking element or forthe portion of the locking element that engages the lock bolt. Whenmounted on te bolt the elastic covering is normally formed as a sleevehaving cylindrical inner and outer surfaces and received in acylindrical outwardly open groove of the lock bolt.

As a door equipped with such a latch is closed the locking-element forkengages and is turned by the lock bolt. The door moves in the closingdirection a certain distance further than its normal rest position,which movement is possible due to the compressibility of the elastomericdoor-edge seal. Thus the door rebounds somewhat against the fork whickby this time is locked securely in position by its lock pawl. The noisethat would normally be created by this springing back against the lockeddoor fork is greatly damped by the synthetic-resin sleeve on the bolt.

The considerable disadvantage of such a system is that thesynthetic-resin covering for the door bolt very quickly wears out. Afteronly a relatively short service life it normally develops a hole in thelocation most often engaged by the locking fork, and normally becomes soloose as to rotate on the door bolt. Eventually this elastomericcovering is damaged to the point where it either falls off or iscompletely useless for absorbing sound.

OBJECTS OF THE INVENTION

It is therefore an object of the present invention to provide animproved door bolt for a motor-vehicle door latch of the above-describedgeneral type.

Another object is to provide such a door bolt which has a longer servicelife and greater noise-damping capacity than the known type.

SUMMARY OF THE INVENTION

These objects are attained according to the instant invention by formingthe lock bolt of a rigid axially extending metal core having a pluralityof annular edges having outer surfaces and defining a plurality ofoutwardly open annular grooves and at least one elastically deformablesynthetic-resin body which fills these grooves and projects radiallytherefrom beyond the outer surfaces of the ridges.

This use of a plurality of such grooves ensures an extremely good holdfor the synthetic-resin body on the metal core and similarly ensuresthat the synthetic-resin body will be relatively thick so as to have along service life. Not only can be synthetic-resin body be deformedradially, but also axially and the portion of it in the grooves belowthe level of the outer surfaces of the ridges can never be badly damagedin use.

According to the instant invention a sleeve having a cylindrical outersurface constitutes the body, the inner surface of the sleeve beingcomplementary to the core between the outer head of the bolt and itsthreaded inner end or shaft. With such an arrangement the portions ofthe sleeve deeply embedded in the grooves of the core will never bysubjected to wear so that the overall life of the elastic body will bevery long. Even if those portions of the sleeve that radially overliethe outer surfaces of the ridges are damaged, the body will continue toabsorb sound effectively. In fact, even if the body becomes worn throughand frayed at the outer surfaces of the ridges it will continue tocushion and absorb sound virtually as well as when new.

It is possible according to this invention to form the ridges andgrooves either separate and annular, or as individual turns of a helicalrecess and helical screwthread formation. The screwthread formation mayhave a trapezoidal section so that the outer surfaces lie on animaginary cylinder parallel to the outer surface of the body. Theprior-art devices having a single annular groove filled with a singlesynthetic-resin body with cylindrical inner and outer surfaces have beenfound to be deficient in that they can squeeze sometimes past the lockbolt even when the door is supposed to be latched. With the systemaccording to the instant invention with a relatively great diameter atthe ridges this type of action is impossible so that the lock issubstantially safer than the prior-art locks.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a vertical section through the lock according to the instantinvention;

FIG. 2 is a section taken along line II--II of FIG. 1;

FIG. 3 is a view, partly in section, taken in the direction of arrow IIIof FIG. 1 through a portion of the assembly of FIG. 1; and

FIG. 4 is a partly sectional side view showing the lock bolt accordingto this invention.

SPECIFIC DESCRIPTION

As seen in FIGS. 1 and 2, a motor-vehicle door edge 10 is normallyseparated by a space 11 from a doorpost 12. A lock bolt indicatedgenerally at D passes through a base plate 13 secured to one side of thedoorpost 12 and is threaded into an anchor plate 17 secured to the otherside of the door edge 12 and secured to the plate 13 by screws 16 seatedin holes 15 in this plate 13. The plate 13 is one leg of a U-shapedelement best seen in FIG. 4, and having another leg 33.

The latch mechanism comprises a standard locking element 18 constitutinga fork having a rear leg 25 and a front leg 24, relative to the closingdirection y of the door, which is opposite the opening direction x (FIG.2). A spring 19 urges this fork 18 counterclockwise, as seen in FIG. 2,so as to normally push the door in the opening direction x. A lock pawl20 urged into engagement with the fork 18 by a spring 23 has anactuating pin 22 that can be operated either by an actuating lever 21connected to the outside door handle or an actuating lever 21a connectedto the inside door handle.

As seen in FIG. 3 the door bolt D according to this invention has asolid steel core K surrounded by a polyester sleeve H. The core K has atone end an enlarged head 27 received in a complementary recess 34 of theleg 33 and a threaded inner end 26 between the two legs 13 and 33 of theU-shaped element 14.

The core K is formed with annular ridges 29 having cylindrical outersurfaces 32 and defining annular grooves 28. The outer surface of thesleeve H is cylindrical and centered on the axis A of the bolt and theinner surface is complementary to the grooves 28 and ridges 29, andextends the full distance between the two legs 13 and 33 of the U-shapedelement 14.

It is also possible, as shown in FIG. 4, to form a core K' with ahelical ridge or screwthread formation 31 of trapezoidal cross sectionand having a cylindrical outer surface 32'. A helical recess 30functionally identical to the grooves 28 is formed by this ridge 31.

As can be seen by comparison of FIGS. 3 and 4 with FIGS. 1 and 2, thesynthetic-resin sleeve 11 will rebound against the inner edge of thefront leg 25 when the door is slammed. Inspite of the considerableabrasion the sleeve H will be subjected to at this location, however, itwill remain well secured to the core K because of the engagement in thegrooves 28 and 30. Even over a long service life good noise damping willbe ensured, since the sleeve will project at least radially beyond theprojections 29 and 31.

I claim:
 1. In a motor-vehicle door lock wherein a lock bolt defining anaxis and normally secured to the doorpost is engaged by a lockingelement normally secured to the door edge to retain the door against thedoorpost, the improvement wherein said bolt is formed of:a rigid axiallyextending metal core having a plurality of annular ridges having outersurfaces and defining a plurality of outwardly open annular grooves, andat least one elastically deformable synthetic-resin body filling saidgrooves and projecting radially therefrom beyond said outer surfaces ofsaid ridges.
 2. The improvement defined in claim 1 wherein said body isa sleeve coaxially surrounding said grooves and said ridges of saidcore.
 3. The improvement defined in claim 2 wherein said outer surfaceslie on an imaginary cylinder centered on said axis.
 4. The improvementdefined in claim 3 wherein each of said ridges and each of said groovesis circularly annular and separate from the respective other ridges andgrooves.
 5. The improvement defined in claim 3 wherein said ridges areturns of a continuous generally helical screwthread formation defining ahelical recess having turns constituting said grooves.
 6. Theimprovement defined in claim 3 wherein said body completely fills saidgrooves.
 7. The improvement defined in claim 3 wherein said body has anenlarged outer head and a threaded inner end, said sleeve lying betweensaid head and inner end.
 8. The improvement defined in claim 7 whereinsaid lock includes a U-shaped plate secured to said door post and havingone leg formed with a recess snugly receiving said head and another legformed with a throughgoing hold through which said shank passes, saidsleeve lying substantially wholly between said legs.
 9. The improvementdefined in claim 8 wherein said lock includes a pivotal lock forkengageable around said bolt in contact only with said sleeve thereof.10. The improvement defined in claim 1 wherein said body is of athermoplastic polyester.